Dither Field

"use client"

import * as React from "react"
import { cn } from "@/lib/utils"
import { Toggle } from "@base-ui/react/toggle"
import { ToggleGroup } from "@base-ui/react/toggle-group"
import { DitherField, FieldMode } from "@/components/ui/dither-field"

const FIT_CSS = "html,body{overflow:hidden}[data-fit-small] [data-fit-hide]{display:none!important}"

/**
 * 21st shows a demo in a small frame: about 674 by 421 on a component page, 358 by 224 on a
 * phone and 245 by 139 on a profile card. A demo taller than its frame gets scrollbars, which
 * render white on dark pages. FitFrame fills the frame exactly instead.
 *
 * - "scale": the content shrinks until it fits, centered. For visuals such as orbs.
 * - "crop": the content stays at full size from the top and fades out at the bottom. For text
 *   that streams in, where a changing scale would make the page breathe.
 *
 * Anything marked `data-fit-hide` (state buttons, the chatcn.dev line) drops out in frames
 * shorter than `hideBelow`, so a profile card shows the visual alone.
 */
function FitFrame({
  children,
  mode = "scale",
  hideBelow = 360,
}: {
  children: React.ReactNode
  mode?: "scale" | "crop"
  hideBelow?: number
}) {
  const content = React.useRef<HTMLDivElement>(null)
  const [cropped, setCropped] = React.useState(false)

  React.useLayoutEffect(() => {
    const el = content.current
    if (!el) return
    const measure = () => {
      const vw = window.innerWidth
      const vh = window.innerHeight
      el.toggleAttribute("data-fit-small", vh < hideBelow)
      // Layout sizes ignore the transform, so measuring never feeds back.
      const w = Math.max(el.offsetWidth, el.scrollWidth)
      const h = Math.max(el.offsetHeight, el.scrollHeight)
      const scale = mode === "scale" ? Math.min(1, vw / w, vh / h) : 1
      el.style.transform = scale < 1 ? `scale(${scale})` : ""
      setCropped(mode === "crop" && h > vh + 1)
    }
    measure()
    const observer = new ResizeObserver(measure)
    observer.observe(el)
    window.addEventListener("resize", measure)
    return () => {
      observer.disconnect()
      window.removeEventListener("resize", measure)
    }
  }, [mode, hideBelow])

  const fade = "linear-gradient(to bottom, #000 calc(100% - 40px), transparent)"
  return (
    <div
      className="flex w-full justify-center overflow-hidden"
      style={{
        height: "100dvh",
        alignItems: mode === "crop" ? "flex-start" : "center",
        maskImage: cropped ? fade : undefined,
        WebkitMaskImage: cropped ? fade : undefined,
      }}
    >
      <style>{FIT_CSS}</style>
      <div
        ref={content}
        className="w-full shrink-0"
        style={{ transformOrigin: mode === "crop" ? "top center" : "center" }}
      >
        {children}
      </div>
    </div>
  )
}

/** A labeled segmented control on Base UI ToggleGroup. One value is always selected. */
function Segmented<T extends string>({
  label,
  value,
  onValueChange,
  options,
  className,
}: {
  label: string
  value: T
  onValueChange: (value: T) => void
  options: readonly { value: T; label: string }[]
  className?: string
}) {
  return (
    <div className={cn("flex min-w-0 flex-col gap-1.5", className)}>
      <span className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-subtle) font-medium">{label}</span>
      <ToggleGroup
        value={[value]}
        onValueChange={(next) => {
          const picked = next[0] as T | undefined
          if (picked) onValueChange(picked)
        }}
        aria-label={label}
        className="bg-(color:--chatcn-fill) rounded-(--chatcn-radius-md) flex h-8 w-fit max-w-full items-center gap-0.5 overflow-x-auto p-0.5 pointer-coarse:h-11"
      >
        {options.map((option) => (
          <Toggle
            key={option.value}
            value={option.value}
            className={cn(
              "chatcn-focus rounded-(--chatcn-radius-sm) text-[0.8125rem]/[1.25rem] inline-flex h-full shrink-0 items-center px-2.5 font-medium whitespace-nowrap",
              "text-(color:--chatcn-fg-subtle) ease-(--chatcn-ease-standard) transition-[color,background-color,box-shadow] duration-150",
              "hover:text-(color:--chatcn-fg) data-[pressed]:bg-(color:--chatcn-card) data-[pressed]:text-(color:--chatcn-fg) data-[pressed]:shadow-(--chatcn-shadow-xs)",
            )}
          >
            {option.label}
          </Toggle>
        ))}
      </ToggleGroup>
    </div>
  )
}

const MODES = [
  { value: "warp", label: "Warp" },
  { value: "simplex", label: "Simplex" },
  { value: "ripple", label: "Ripple" },
] as const satisfies readonly { value: FieldMode; label: string }[]

/** A living field in a media frame. Ripple follows the pointer. Pause sits in the corner. */
function DitherFieldDemo() {
  const [mode, setMode] = React.useState<FieldMode>("warp")
  return (
    <div className="flex w-full max-w-2xl flex-col gap-5">
      <DitherField mode={mode} className="rounded-(--chatcn-radius-lg) aspect-video w-full" />
      <Segmented label="Mode" value={mode} onValueChange={setMode} options={MODES} />
    </div>
  )
}

/** The line under each 21st demo that points back to the kit. */
function MoreOn({ slug, children }: { slug: string; children: React.ReactNode }) {
  return (
    <p data-fit-hide className="text-[0.75rem]/[1rem] text-(color:--chatcn-fg-faint) text-center text-balance">
      {children}{" "}
      <a
        href={`https://chatcn.dev/docs/components/${slug}`}
        target="_blank"
        rel="noopener"
        className="text-(color:--chatcn-fg-subtle) hover:text-(color:--chatcn-fg) underline underline-offset-2"
      >
        chatcn.dev
      </a>
    </p>
  )
}

export default function DitherFieldPreview() {
  return (
    <FitFrame>
      <div className="flex w-full flex-col items-center justify-center gap-10 p-6">
        <DitherFieldDemo />
        <MoreOn slug="dither-field">
          Warp, simplex and ripple fields with a pause control. More on
        </MoreOn>
      </div>
    </FitFrame>
  )
}